car won't start

i have a 1991 eldorado with about 142,000 miles. it's the 4.9 liter engine. my starter went out, i changed it, and it ran for about 25 miles, until i ran out of gas. i put 5 gallons in, and now it won't start. i've tried replacing the starter again, adjusting with shims, i've checked to make sure there is power going to the starter, and i need some advice on what to check to get it running. any help would be greatly appreciated.